wT 1255/12
Page 14
11
Service and Maintenance
Maintenance and inspection intervals are to be determined by the operator dependent
on the operating mode, as these valves can be utilized under a number of different
operating conditions. Maintenance and inspection work may only be carried out by
trained personnel.
Prior to the start of service and maintenance work, it must be ensured that the pipeline
system is depressurized and that no medium residues are contained within.
Should a valve become leaky, the tightening torques of the bonnet securing nuts must
be compared to the tightening table. Retightening may be necessary. Prior to doing so,
the valve must be brought into the CLOSED position.
Care should be taken to keep the spindle thread sufficiently lubricated at all times. Please
refer to chapter 11.5 for suitable lubricants.
In the event that the spindle thread shows a high degree of wear the valve should be
depressurized and maintenance carried out.
When removing an actuator, it is necessary to protect it against rotation prior to loosening
of the connecting screws.